Heretofore, various types of heat exchangers utilizing heat pipes which transfer heat from a high temperature fluid to a low temperature fluid have been developed.
As a typical one thereof, a fixed-type heat pipe heat exchanger is known wherein a group of heat pipes are arranged in box form and the central part thereof is partitioned, a high temperature fluid being let to flow into one and a low temperature fluid into the other one, respectively, so that, by the specific properties of the heat pipes, the heat given from the high temperature fluid is transferred to the low temperature fluid through the sealed-in fluid in the heat pipes.
However, if this kind of fixed-type heat pipe heat exchanger is used to recover heat effectively from the combustion gases containing dust, sulfur oxide (SO.sub.x) and nitrogen oxide (NO.sub.x) at high concentration exhausted from large-sized boilers or industrial furnaces for steam-power plant, then, as shown in FIG. 1, these dust and the like adhere to the gaps of a number of fins 2 attached to the outside of heat pipes 1 on the high temperature side to blockade the passage for the high temperature gas, and, also, the surface temperature of the heat pipes on the high temperature fluid side drops below the acid dew point temperature of the exhaust gas, so that the sulfuric acid content in the exhaust gas condenses to adhere to the surface of the heat pipes, this having been the cause of corroding the heat pipes.
Accordingly, the present invention, being one accomplished in view of the above-mentioned circumstances, has for its object the providing of a fixed-type heat pipe heat exchanger which can be used to recover heat from the combustion gases containing dust, sulfur oxide (SO.sub.x) and the like at high concentration exhausted from a large-sized boiler or the like of a steam-power plant and utilize the heat effectively, and wherein the gas passages are not blocked up by dust and the like and yet the heat pipes are not corroded by the sulfuric acid content in the exhaust gas.